Internal combustion engines can operate on multiple types of gaseous fuels such as petroleum-based propane gas and butane gas. Unfortunately, propane gas and butane gas have different calorific values and therefore must be provided to the engine at specific pre-determined pressures dependent upon the type of gas. Because specific gasses must flow at specific pressures the ability of an engine to run utilizing a variety of different fuels is somewhat moot because an easy and economical means of varying fuel supply pressures to correspond to different gas types is not available.